A compound represented by formula (I) or a salt thereof. ##STR00001## In formula (I), R.sup.1 and R.sup.4 each independently represent a hydrogen atom, or an unsubstituted or substituted C1 to C6 alkyl group or the like. R.sup.2 represents a hydrogen atom, or an unsubstituted or substituted C1 to C6 alkyl group or the like. R.sup.3 represents an unsubstituted or substituted C1 to C6 alkyl group or the like. R.sup.5 represents a C1 to C6 haloalkyl group or the like. G represents an oxygen atom or a sulfur atom. R.sup.6 and R.sup.7 each independently represent a hydrogen atom, or an unsubstituted or substituted C1 to C6 alkyl group or the like. n represents 0 or 1. R.sup.8 and R.sup.9 each independently represent a hydrogen atom, or an unsubstituted or substituted C1 to C6 alkyl group. Ar represents an unsubstituted or substituted C6 to C10 aryl group or the like.

A method for preparing isophorone diisocyanate by (1) reacting isophorone with hydrogen cyanide in the presence of a catalyst to obtain isophorone nitrile; (2) reacting the isophorone nitrile obtained in step (1) with ammonia gas and hydrogen in the presence of a catalyst to obtain isophorone diamine; and (3) subjecting the isophorone diamine to a phosgenation reaction to obtain the isophorone diisocyanate, wherein the content of impurities containing a secondary amine group in the isophorone diamine that undergoes the phosgenation reaction in step (3) is ?0.5 wt. The method reduces the content of hydrolyzed chlorine in the isophorone diisocyanate product, improves the yellowing resistance of the product, and the harm due to presence of hydrolyzed chlorine in the product is reduced.

Chiral acetyl-protected aminoethyl quinoline (APAQ), pyridine and imazoline ligands are disclosed that enable Pd (II)-catalyzed enantioselective arylation or heteroarylation of ubiquitous prochiral -methylene CH bonds of aliphatic amides offers an alternative disconnection for constructing -chiral centers. Systematic tuning of the ligand structure reveals that a six-membered instead of a five-membered chelation of these types of ligands with the Pd(II) is important for accelerating the C(sp.sup.3)-H activation thereby achieving enantioselectivity for quinoline and pyridine ligands.

Chiral acetyl-protected aminoethyl quinoline (APAQ), pyridine and imazoline ligands are disclosed that enable Pd (II)-catalyzed enantioselective arylation or heteroarylation of ubiquitous prochiral -methylene CH bonds of aliphatic amides offers an alternative disconnection for constructing -chiral centers. Systematic tuning of the ligand structure reveals that a six-membered instead of a five-membered chelation of these types of ligands with the Pd(II) is important for accelerating the C(sp.sup.3)-H activation thereby achieving enantioselectivity for quinoline and pyridine ligands.

A compound represented by formula (I) or a salt thereof.

##STR00001##

In formula (I), R.sup.1 and R.sup.4 each independently represent a hydrogen atom, or an unsubstituted or substituted C1 to C6 alkyl group or the like. R.sup.2 represents a hydrogen atom, or an unsubstituted or substituted C1 to C6 alkyl group or the like. R.sup.3 represents an unsubstituted or substituted C1 to C6 alkyl group or the like. R.sup.5 represents a C1 to C6 haloalkyl group or the like. G represents an oxygen atom or a sulfur atom. R.sup.6 and R.sup.7 each independently represent a hydrogen atom, or an unsubstituted or substituted C1 to C6 alkyl group or the like. n represents 0 or 1. R.sup.8 and R.sup.9 each independently represent a hydrogen atom, or an unsubstituted or substituted C1 to C6 alkyl group. Ar represents an unsubstituted or substituted C6 to C10 aryl group or the like.

The enantioselective synthesis of isochroman motifs has been accomplished via Pd(II)-catalyzed allylic CH oxidation from terminal olefin precursors. Critical to the success of this goal was the development and utilization of a novel chiral aryl sulfoxide-oxazoline (ArSOX) ligand. The allylic CH oxidation reaction proceeds with the broadest scope and highest levels asymmetric induction reported to date (avg. 92% ee, 13 examples 90% ee). Additionally, C(sp.sup.3)-N fragment coupling reaction between abundant terminal olefins and N-triflyl protected aliphatic and aromatic amines via Pd(II)/sulfoxide (SOX) catalyzed intermolecular allylic CH amination is disclosed. A range of 52 allylic amines are furnished in good yields (avg. 76%) and excellent regio- and stereoselectivity (avg. >20:1 linear:branched, >20:1 E:Z). For the first time, a variety of singly activated aromatic and aliphatic nitrogen nucleophiles, including ones with stereochemical elements, can be used in fragment coupling stiochiometries for intermolecular CH amination reactions.

The enantioselective synthesis of isochroman motifs has been accomplished via Pd(II)-catalyzed allylic CH oxidation from terminal olefin precursors. Critical to the success of this goal was the development and utilization of a novel chiral aryl sulfoxide-oxazoline (ArSOX) ligand. The allylic CH oxidation reaction proceeds with the broadest scope and highest levels asymmetric induction reported to date (avg. 92% ee, 13 examples 90% ee). Additionally, C(sp.sup.3)-N fragment coupling reaction between abundant terminal olefins and N-triflyl protected aliphatic and aromatic amines via Pd(II)/sulfoxide (SOX) catalyzed intermolecular allylic CH amination is disclosed. A range of 52 allylic amines are furnished in good yields (avg. 76%) and excellent regio- and stereoselectivity (avg. >20:1 linear:branched, >20:1 E:Z). For the first time, a variety of singly activated aromatic and aliphatic nitrogen nucleophiles, including ones with stereochemical elements, can be used in fragment coupling stiochiometries for intermolecular CH amination reactions.

The discovery of distinct modes of asymmetric catalysis has the potential to rapidly advance chemists' ability to build enantioenriched molecules. As an example, the use of chiral cation salts as phase-transfer catalysts for anionic reagents has enabled a vast set of enantioselective transformations. A largely overlooked analogous mechanism wherein a chiral anionic catalyst brings a cationic species into solution is itself a powerful method. The concept is broadly applicable to a number of different reaction pathways, including to the enantioselective fluorocyclization of olefins, and dearomatization of aromatic systems with a cationic electrophile-transferring (e.g., fluorinating) agent and a chiral phosphate catalyst. The reactions proceed in high yield and stereoselectivity. The compounds and methods of the invention are of particular value, especially considering the scarcity of alternative approaches.

The discovery of distinct modes of asymmetric catalysis has the potential to rapidly advance chemists' ability to build enantioenriched molecules. As an example, the use of chiral cation salts as phase-transfer catalysts for anionic reagents has enabled a vast set of enantioselective transformations. A largely overlooked analogous mechanism wherein a chiral anionic catalyst brings a cationic species into solution is itself a powerful method. The concept is broadly applicable to a number of different reaction pathways, including to the enantioselective fluorocyclization of olefins, and dearomatization of aromatic systems with a cationic electrophile-transferring (e.g., fluorinating) agent and a chiral phosphate catalyst. The reactions proceed in high yield and stereoselectivity. The compounds and methods of the invention are of particular value, especially considering the scarcity of alternative approaches.

A method for synthesizing florfenicol comprises the steps of cyclization, selective reduction, fluorination, ring opening, deprotection, acylation, esterification with sulfonic acids, epimerization and hydrolysis. Florfenicol is prepared by successively purifying, selectively reducing, and epimerizing chiral (R)-amino ketones. This improves atom economy, reduces waste water pollution and accordingly reduces costs for treating waste water and pollution to the environment, thus lowering costs and simplifying the process. Furthermore, triethylamine hydrofluoride is used as a fluorinating reagent, resulting in improved safety, because of the use of liquid reaction conditions as compared to gaseous reaction conditions, and reduced corrosion to the reaction equipment.